When I rented a place in Cambridge in 2019, the rent was $3200/month. To get the lease signed I had to write a check for 4x that amount (first+last+security deposit+broker fee). $12,800 before even dealing with any moving costs.
The worst thing about it is that it increases the cost of moving very significantly. So people are coerced into accepting large rent increases as long as the increase is less than forking out another broker fee to move to a cheaper apartment.
In the end, I'm not sure it's that bad. I moved to NYC in early 2012. I found a rent-stabilized apartment with the help of a broker, and paid about $600 less per month than a market rate apartment. I paid $3000 to my broker, and conservatively saved about $79,200 over the lifetime of the apartment lease relative to equivalent market-rate apartments.
There was supposed to be a crackdown on the practice in NYC in 2020, but the brokers lobby was too powerful.[0]
One can only hope that such legislation eventually passes -- and has teeth.
[0]: https://www.nytimes.com/2021/05/27/nyregion/broker-fees-real...